Not that the ratings mean much, but probably when they rated Heracross he was a 4, given the only other real option for fighting-type damage was Machamp, whereas now you've also got Breloom and Hariyama, so in this new meta Lucario is only a 3. They probably just haven't updated Heracross' rating to account for Gens 3 and 4.
GamePress
Heracross rated 4 but Lucario rated 3?
Heracross is nearly identical to Lucario in terms of performance, and Heracross is actually just as viable as a bug attacker as Lucario is a steel attacker (Which means both are not viable as those). Both aren't exactly commonly seen stuff either, and perform in similar effectiveness with the terrible counter close combat combo.
Maybe downgrade Heracross to 3 or upgrade lucario to 4 (Or even give both a 3.5?)
